Advantage Century Telecommunication, Broadband Utilities, Jasomi and Leapstone Systems Join OSPA; New Partners Share OSPA Goal of Facilitating End-to-End Packet Voice Deployments

WESTFORD, Mass., June 17, 2002 - Sonus Networks (Nasdaq: SONS), a leading provider of voice infrastructure solutions for the new public network, continues to broaden the company's Open Services Partner AllianceSM (OSPA) with the addition of four new members. Joining the program today are Advantage Century Telecommunication, Broadband Utilities (BBU), Jasomi Networks and Leapstone Systems.

The OSPA is comprised of leading telecom hardware and software providers offering a vast array of products such as enhanced services, network infrastructure and operations support systems (OSS). Sonus' newest partners further expand the offerings delivered through the OSPA, with solutions ranging from IP telephones to carrier application management systems to SIP peering technologies.

"Each member company brings a unique solution to the Alliance and assists our customers in delivering exciting new services to end users," said Terri Griffin, vice president, marketing, Sonus Networks. "Together with our partners, we are helping carriers deliver on the promise of the new public network by making it easier to deploy an extensive range of voice and data solutions."

The newest partners in the OSPA provide the following solutions and services:

• Advantage Century Telecommunication provides a range of IP-based products including IP phones, terminal adapters, a VoIP 4/8 port gateway and IADs that combine the reliability and high quality of traditional voice communication with the flexibility and extensibility of the Internet Protocol (IP) and packet transmission. (www.act-tel.com.tw)
• Broadband Utilities offers the INtelligentACD platform, which provides flexible call distribution and SS7 routing for network operator services and other applications. The INtelligentACD platform provides intelligent call routing to both automated and manned operator consoles, including billing and statistics. (www.broadbandutilities.com)
• Jasomi Networks delivers the PeerPoint SIP-to-SIP gateway, which resides at the edge of the network and enables the traversal of NAT firewalls, call hiding and route anonymization, and provides a platform for CALEA regulatory requirements. (www.jasomi.com)
• Leapstone Systems offers the Communications Convergence Engine (CCE), a streamlined service introduction solution for wireline and wireless service providers. The CCE enables service providers to quickly adopt new applications, protecting and enhancing the existing PSTN network investment while introducing new IP and wireless applications. It coordinates the intricacies of resource management, service bundling, transaction monitoring and billing flows for large service provider networks. (www.leapstone.com)

About Sonus' OSPA

Sonus Networks' Open Services Partner Alliance program provides a framework that offers service providers end-to-end packet-based network solutions using best-of-breed technologies and applications. The goal of the OSPA is to empower standards-based interoperability between applications, hardware vendors, and the Sonus product family. An integral part of the Sonus OSPA, the OSPA Interoperability Laboratory is the first in the industry where product interoperability is verified, trial testing is performed and complete solutions are ultimately produced. To find additional information on the OSPA, including a list of all OSPA partners, log on to http://ospa.sonusnet.com.

About Sonus Networks

Sonus Networks, Inc., is a leading provider of packet voice infrastructure products for the new public network. With its Open Services Architecture (OSA), Sonus delivers end-to-end solutions addressing a full range of carrier applications, including trunking, residential access and Centrex, tandem switching, and IP voice termination, as well as enhanced services. Sonus' award-winning voice infrastructure solutions, including media gateways, softswitches and network management systems, are deployed in service provider networks worldwide. Sonus, founded in 1997, is headquartered in Westford, Massachusetts. Additional information on Sonus is available at http://www.sonusnet.com.

This release may contain projections or other forward-looking statements regarding future events or the future financial performance of Sonus that involve risks and uncertainties. Readers are cautioned that these forward-looking statements are only predictions and may differ materially from actual future events or results. Readers are referred to Sonus' Quarterly Report on Form 10-Q, dated May 10, 2002 and filed with the SEC, which identifies important risk factors that could cause actual results to differ from those contained in the forward-looking statements. These risk factors include, among others, the adverse effect of recent developments in the telecommunications industry, the weakened financial position of many emerging service providers, Sonus' ability to grow its customer base, dependence on new product offerings, market acceptance of its products, rapid technological and market change and manufacturing and sourcing risks.

Open Services Partner Alliance is a service mark of Sonus Networks and Open Services Architecture is a trademark of Sonus Networks. All other company and product names may be trademarks of the respective companies with which they are associated.